11/05/18: PHP Web Shell dbs.php

Threat Summary

Overview

The shell is a simple uploader generally used as a first stage before uploading different pieces of malicious software. The dbs.php shell is related to a campaign against CVE-2018-1000207, a remote code execution attempt against Modx revolution.

Exploitation

Stages

An attacker uploads a PHP web shell to the vulnerable server via an upload mechanism or vulnerability.

The server will respond indicating a successful upload.

The attacker will utilize the shell’s functionality to take action upon their objectives.

Prerequisites

The attacker must be able to send crafted packets to the target system.

Vulnerability Description

The dbs.php shell can be uploaded to a server via an upload mechanism or vulnerability. The shell is a simple uploader that is generally used as a first stage before uploading different pieces of malicious software.

Alert Logic Coverage

Alert Logic® has evaluated its customer base for exposure to the exploit and has developed signatures for mitigating the threat depending on the security service in place.

The Network-Based Intrusion Detection System (IDS) has been updated with the new signatures for this exploit when detected via Alert Logic Threat Manager™. If this signature is detected, an incident is generated in the Alert Logic console.

Recommendations for Mitigation

The attacker must have exploited some other entry vector to allow the malicious files to become resident on the victim machine.